Physical evidence cannot be intimidated. It does not forget. It sits there and waits to be detected, preserved, evaluated and explained.
Chemical Forensics
Classical verification analysis is concerned with the presence or the absence of relevant substances in a sample and the preservation and exploitation of forensic signatures is not a prime concern. However, when sample analysis tries to contribute to answering the question about the source of a chemical or the perpetrator of an attack these signatures become highly relevant pieces of information. Chemical forensics tries to analyze and designate these signatures.
Impurity profiling
A major chemical attribution signature is often not the agent itself, nor its direct degradation products, but minor impurities carried through the production process from the raw materials or formed during a production step. Apart from detecting such impurities and comparing them to a reference (ideally the raw materials or reactor content), it is of key importance to understand how these signatures are affected by environmental conditions such as air and moisture and which parts of the signature are robust to environmental conditions.
Computational methods are important in the assessment of chemical impurity signatures through chemometrics and while a perfect solutions might not always be possible it must be recognized that even semi-perfect answers might be of high relevance (e.g. the exclusion of possible sources, synthesis routes, raw materials).
Stable isotope ratios
Many elements in nature occur as a mixture of stable isotopes (e.g. 1H/2H, 12C/13C or 16O/18O). Depending on the source material and certain processing steps very small but characteristic differences in these isotope ratios are observed and can be exploited as a forensic signature.
Isotope-ratio techniques have been successfully applied in the food industry to check for adulteration honey, orange juice or wine. The techniques also find application in forensic applications. In the field of CW agents, precursors or degradation products their application is relatively new and an area of active research.
In the past special isotope ratio mass spectrometers were used (IRMS) but these were unable to yield site-specific (or atom specific ratios). Modern Orbitrap instruments can reused alternatively giving such information or NMR can be used (SNIF-NMR). This is of high relevance for example for nerve agents like Sarin where one precursor (Isopropanol) will have a different 12C/13C ratio that the other precursor (DF) resulting in two different characteristic signature in the resulting Sarin molecule.
We provide method development and method validation for clients with respect to chemical forensics applications. This applies to both impurity profiling as well as stable isotope rations (employing IRMS, Orbitraps and SNIF-NMR).
We are providing special expertise regarding the site-specific isotope ratios using NMR and Orbitrap MS.
We help clients to develop a chemical forensics portfolio that enables them to provide science based provenancing of samples-.